The object of the present invention is a sprayer for liquids, in particular a pump sprayer actuated manually by means of a trigger lever, provided with a system of precompression suitable for expelling the liquid with a greater speed or acceleration.
A sprayer generally comprises a main body provided with a base with a threaded ring nut or with bayonet coupling to be attached to the mouth of a container of liquid, a delivery nozzle wherefrom the liquid is sprayed, a trigger lever which can be actuated by hand by the user and a pump which can be actuated by the trigger lever to aspirate the liquid from the container by means of a dipper tube and spray it via the delivery nozzle.
The pump provides a piston acting in a chamber formed in the body of the sprayer. The body of the sprayer comprises moreover an inlet duct which places in communication the interior of the container of the fluid with the chamber of the pump and an outlet duct which places in communication the chamber of the pump with the nozzle of the sprayer. A valve for fluid suction and delivery is provided inside or immediately upstream of the chamber of the pump, suitable for allowing in a selective and one-way manner the suction of the fluid from the container to the chamber of the pump and the delivery of fluid from the chamber of the pump towards the delivery nozzle.
In order to accelerate the exiting of the liquid from the sprayer, or to guarantee a regular jet of the liquid, normally nebulised, aside from the speed of actuation of the trigger lever, systems of precompression have been proposed, which co-operate with the piston actuated by the lever in order to increase the pressure of delivery of the liquid.
These known systems of precompression normally require numerous additional components in order to obtain the desired effect, with consequent increase in the cost of production. They are also somewhat complex and not easy to produce.
One example is represented by the lever sprayer device described in WO 96/18572 which, when the pump is actuated, releases the air from a chamber of the sprayer inside a container whereto the sprayer is connected. This device comprises a piston assembly defined by a pump-piston sliding inside a pump-chamber and by a release piston integrated in the pump-piston and slidingly positioned inside a release chamber, a pressure regulator sliding inside a channel and suitable for allowing the passage under pressure of the liquid directed towards the sprayer nozzle, with said pressure regulator comprising a valve sliding on a pin provided with peripheral grooves and formed in said channel for the passage of the liquid and a contrast spring positioned around said pin.
When the pump-piston is actuated manually by acting on the manual lever, it takes the liquid to be sprayed from the receptacle and pushes it against the valve thus causing a force of pressure on the same which slides in relation to the pin and, overcoming the action of contrast of the spring, allows the passage of the fluid via the grooves of the pin in the direction of the spray nozzle. The liquid impacts against the side wall of the valve and causes the raising thereof, acting against a membrane projecting perimetrically from the same.
This known solution, however, has some important disadvantages linked to the fact that it is presented as a complex and costly device as regards manufacture and, moreover, requires the prior evacuation of the air contained in the pumping chamber not sufficient for allowing the raising of the valve and, only when said chamber is filled with the liquid aspirated from the container, the raising of the valve takes place and therefore the system of precompression starts to function.
The object of the invention is that of providing a sprayer for liquids with system of precompression which is simple and economical to manufacture and highly reliable.
Another object of the invention is that of providing such a system of precompression which can easily be adapted, with few actions, to existing sprayers.
In particular the system of precompression that forms the object of the invention constitutes an improvement of the sprayer for liquids that is the object of the European patent EP 1585602, which is incorporated herein by reference in its entirety.